The present invention relates to bacteria cultivation and dispensing systems, and more particularly to an automatic bacteria cultivation and dispensing system that is useful for incubating bacteria from a starter population to a utility population within a predetermined interval and thereafter dispensing sufficient bacteria to perform a desired utility. A preferred utility for the disclosed system is the removal of grease from grease traps in commercial food preparation establishments.
In the environment, bacteria are constantly working to naturally break down organic materials. This natural process generally causes some organic materials to eventually degrade into carbon dioxide and water. Under normal conditions, competition for resources, limited supplies of nutrients, and natural enemies can combine to inhibit rapid bacterial growth. By isolating selected strains of bacteria and providing a food source they prefer, bacteria can be made to multiply at a very fast rate. A large quantity of bacteria can be generated in this manner within a relatively short time. The bacteria can then be used in a wide variety of applications where the breakdown of organic materials is desirable.
One application where the breakdown of organic materials is particularly useful is in the maintenance of grease traps. Grease traps are required on virtually all commercial facilities that discard liquid or solid grease into a sewer system. Grease traps generally range from a capacity of about five gallons to over several thousand gallons. The majority of fast food kitchens are equipped with grease traps of about 1000 gallons. The system of drains used for grease traps is generally separate from the drains that carry away waste products from restrooms, spent drinking water, etc. Grease traps tend to collect not only oils and fats, but also various organic waste materials such as starches and vegetable waste products. Normally, a significant flow of wastewater is also introduced into the separate grease trap drainage system from kitchen drains where grease is often found. To prevent the wastewater from flushing grease into the city sewer system, grease traps are designed with a series of weirs that trap the grease within the containment vessel and allow wastewater to pass through the vessel on to a city treatment facility.
Inevitably, however, some of the grease in the grease trap passes into the city sewage system downstream from the restaurant. This does not create problems if the amount of grease passing into the sewer system is kept at a low level. Most city standards restrict the release of grease into sewer lines to approximately 250 ppm or less. If significant amounts of grease pass into the sewage system, the grease can cause blockages in the city pipes. When this occurs, the grease trap can overflow into the street, causing health problems. City maintenance crews often have to dig up the pipes under the street to remove the blockage. The cost of this procedure is typically passed on to the restaurant that released the grease. The restaurant usually must also pay a fine. For repeat offenders, the blockage can result in closure of the facility.
To avoid such problems, the current practice is to periodically collect the solid grease that floats on the top of the grease trap. In addition, every four to eight weeks, a service company should remove grease and other solid material that has settled and accumulated in the bottom of the grease trap, and should steam strip the walls and weirs. The cost of this service varies depending on the geographical region and the contract agreed upon by the restaurant owner and the service company, but is substantially greater over time than will be required using the system and method disclosed herein. If the grease trap is not pumped out on a regular basis, the grease layer can form such a thick crust that it blocks the inlet line into the grease trap and causes wastewater to back up into the facility. Such a back-up can require closing the restaurant or facility until the problem is resolved. Because of the potential fines and the possibility of temporary or permanent closure, maintenance of grease traps is of great importance to the owners of commercial food preparations establishments.
There are currently several products on the market that purportedly reduce the number of pump-outs needed. Many of these products are solvent-based or are detergents containing enzymes that will allegedly make the grease trap maintenance free. While many of these solvents or detergent products will dissolve the grease in the grease trap, the liquified grease often resolidifies a few feet down the sewage pipes, thereby blocking the flow of wastewater.
Another known device for treating grease traps uses bacteria in an attempt to digest the grease. The device includes a five gallon bucket that contains a bacterial gel material. Water continuously flows through the bucket and into the drain system. A disadvantage of this device is that most of the bacteria is introduced into the grease trap during periods of high kitchen activity. The volume of wastewater that flows through the grease trap flushes most of the bacteria through the grease trap and into the sewer system before the bacteria is able to digest the grease. In addition, a typical grease trap is generally a poor environment for growing bacteria rapidly due to a lack of oxygen, as well as the presence of contaminants such as detergents and antibacterial chemicals used in cleaning operations.
Another known treatment is to introduce preserved bacteria into the grease trap. This type of bacteria is generally in the form of a dry powder that consists of dormant bacteria spores. Before the growth of bacterial colonies can occur, these dormant spores must go through an incubation period to form active vegetative cells. This process takes about six hours to occur. If the spores are introduced into the grease trap before this time, most of the bacteria will be flushed from the grease trap before digestion can occur.
Another known method of maintaining a grease trap is to grow large quantities of active bacteria offsite using a filtered air supply, distilled water, and a specially designed growth chamber. The large amount of bacteria needed to sufficiently digest the grease in the grease trap, however, has not been affordable because large volumes of bacteria are expensive to produce and difficult to transport.
Applicants"" copending application Ser. No. 09/031,642, filed Feb. 27, 1998, discloses an inexpensive and simple system and method for producing and dispensing large quantities of selected strains of bacteria into grease traps. That system and method are used to produce bacteria onsite in a favorable growth environment and to automatically dispense a predetermined volume of liquid containing active bacteria into the grease trap drain system during the night or at other times when flow through the trap is minimal. During use of that system, however, excessive foaming can occur in the biogeneration chamber even in the presence of an antifoaming agent due to the continuous introduction of air needed for bacterial growth through a tube having its discharge end submerged in the bacteria cultivation mixture. Such excessive foaming can cause the biogeneration chamber to overflow through the vent line, causing loss of nutrients, water and cell count, thereby slowing the desired bacterial growth.
Prior art devices said to be useful for aerating a cultivation medium within a tank, vessel or container to promote fermentation or bacterial growth are disclosed, for example, in U.S. Pat. Nos. 4,051,204; 4,426,450; 4,883,759; and 4,888,294.
The present invention comprises an automated biogeneration system and method for producing and dispensing liquid concentrates of active bacteria at predetermined intervals. According to a preferred embodiment of the invention, bacteria produced in this manner can be used to digest organic material in a grease trap and to reduce the frequency of pump-outs required. The system and method of the invention can also be used to supply bacteria for many other useful applications as disclosed below.
According to one preferred embodiment of the invention, a method for growing and selectively discharging bacteria is disclosed whereby water and a predetermined quantity of a powdered mixture of dehydrated xe2x80x9cstarterxe2x80x9d bacteria and appropriate nutrient(s) are automatically introduced into a biogeneration chamber for the purpose of growing and quickly multiplying the selected bacteria. Multiple strains of bacteria can be used as long as the nutrient package is designed to support each of the multiple strains. Pressurized air is supplied to the chamber to support aerobic bacterial reproduction, and is desirably introduced according to a special method using a vortex that controls foaming within the biogeneration chamber. After the mixture is placed in the biogeneration chamber, the bacteria are permitted to grow and reproduce for a desired time, such as about 24 hours, while continually withdrawing liquid from the bottom of the chamber, recirculating it with a pump, and reintroducing it into the chamber in a tangentially directed flow to create the desired vortex. At the end of the growing period, the active bacteria are preferably discharged from the biogeneration chamber to another holding vessel or, more preferably, directly to a use site such as a restaurant grease trap. Once the contents of the biogeneration chamber are discharged, the process is repeated. The cycle of operation is desirably controlled by an electronic timer having relays that activate and deactivate switches and valves in accordance with predetermined parameters. Significant increases in bacterial production are observed using the system and method disclosed herein as compared to applicants"" previously disclosed system and method.
According to another preferred embodiment of the invention, an automated batch system for growing and selectively discharging a bacteria-containing fluid is disclosed that comprises a biogeneration chamber having a substantially cylindrical sidewall, a top and a conical bottom, a feed source communicating with a feed inlet port in the top, a water source communicating with a water inlet port in the top, a pressurized air source communicating with an air inlet port in the top, a vent line communicating with a vent port in the top, a centrally disposed outlet port in the conical bottom, an orifice element disposed in the conical bottom at or near the outlet port, a recirculated fluid inlet port positioned and directed so as to reintroduce recirculated fluid into the chamber in a substantially tangential direction relative to the inside wall, a recirculating pump, flow tubing placing the recirculating pump inlet in fluid communication with the chamber outlet port and placing the recirculating pump outlet in fluid communication with the recirculated fluid inlet port, and a valve disposed in the flow tubing between the recirculating pump and the recirculated fluid inlet port to selectively divert flow from the pump to a drain line also communicating through the pump and the valve with the chamber outlet port.